> Could you please tell me how the audience will be selected and what settings will be available to the advertiser? 

Bid events carry a [set of metadata](https://ngengine.org/docs/nip-drafts/nip-ADS/#bidding-event) for the ads, that's how the advertiser can hint for an audience. 

In addition to that every user is defined by an anonymous pubkey and every request carry an app pubkey, so the advertiser can target a specific app and a set of users without knowing exactly who they are.

> Will there be an auction system if two advertisers target the same viewer?

This is client-side and is mostly implementation specific, in my implementation bids are ranked based on how many sats they pay, how well they fit the adspace, how many times they have been shown and by the honesty of the advertiser.

rblb

nostr

I built a decentralized Advertising Network protocol on Nostr

I think I understood everything, but no.
Could you please tell me how the audience will be selected and what settings will be available to the advertiser? Will there be an auction system if two advertisers target the same viewer? What targeting options will be available in general? Thank you!